{"answers":{"affected":"4 open source packages ship an affected version, including @fastify/http-proxy and @fastify/reply-from. It affects 2 products.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33805 exists.","fix":"Upgrade @fastify/http-proxy to 11.4.4 or later.","what":"CVE-2026-33805 is a critical vulnerability in @fastify/reply-from @fastify/http-proxy, published on 15 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-33805 and fix it if it is affected.\n\nWhat it is: CVE-2026-33805 is a critical vulnerability in @fastify/reply-from @fastify/http-proxy, published on 15 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33805 exists.\n\nAffected packages and fixed versions:\n- @fastify/http-proxy (npm): affected all versions; fixed in 11.4.4\n- @fastify/http-proxy (npm): affected all versions; fixed in 11.4.4\n- @fastify/reply-from (npm): affected all versions; fixed in 12.6.2\n- @fastify/reply-from (npm): affected all versions; fixed in 12.6.2\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-33805/ (Markdown: https://insights.sbomify.com/CVE-2026-33805/index.md)","id":"CVE-2026-33805","markdown":"https://insights.sbomify.com/CVE-2026-33805/index.md","name":"CVE-2026-33805","record":{"aliases":["GHSA-gwhp-pf74-vj37"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Fastify proxy library","requires_auth":"none","summary":"Attackers can strip proxy-added security headers by abusing the Connection header, bypassing access controls in Fastify proxy libraries.","user_interaction":"not_required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"openjs","cpe":[{"product":"fastify\\/http-proxy","vendor":"fastify"},{"product":"reply-from","vendor":"fastify"}],"cvss":{"score":9,"severity":"critical","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N","version":"4.0"},"cwes":[{"id":"CWE-444","name":"Inconsistent Interpretation of HTTP Requests"},{"id":"CWE-644","name":"Improper Neutralization of HTTP Headers for Scripting Syntax"}],"description":"@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers from upstream requests by listing them in the Connection header value. Any header added by the proxy for routing, access control, or security purposes can be selectively removed by a client. @fastify/http-proxy is also affected as it delegates to @fastify/reply-from. \n\nUpgrade to @fastify/reply-from v12.6.2 or @fastify/http-proxy v11.4.4 or later.","ecosystems":["npm"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"@fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headers","id":"CVE-2026-33805","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":null,"products":[],"type":"security_feature_bypass","year":"2026"},"n_packages":4,"n_references":2,"next":{"headline":"fastify vulnerable to Body Schema Validation Bypass via Leading Space in Content-Type Header","id":"CVE-2026-33806"},"packages":[{"ecosystem":"npm","fixed":["11.4.4"],"introduced":["0"],"last_affected":[],"package":"@fastify/http-proxy","purl":null,"source":"GHSA-gwhp-pf74-vj37"},{"ecosystem":"npm","fixed":["11.4.4"],"introduced":["0"],"last_affected":[],"package":"@fastify/http-proxy","purl":"pkg:npm/%40fastify/http-proxy","source":"GHSA-gwhp-pf74-vj37"},{"ecosystem":"npm","fixed":["12.6.2"],"introduced":["0"],"last_affected":[],"package":"@fastify/reply-from","purl":null,"source":"GHSA-gwhp-pf74-vj37"},{"ecosystem":"npm","fixed":["12.6.2"],"introduced":["0"],"last_affected":[],"package":"@fastify/reply-from","purl":"pkg:npm/%40fastify/reply-from","source":"GHSA-gwhp-pf74-vj37"}],"prev":{"headline":"@fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option","id":"CVE-2026-33804"},"products":["@fastify/http-proxy","@fastify/reply-from"],"published":"2026-04-15","related":[{"cvss_score":10,"headline":"@fastify/http-proxy vulnerable to prefix escape via URL-encoded characters","id":"CVE-2026-16117","kev_date_added":null,"published":"2026-07-18"},{"cvss_score":8.7,"headline":"@fastify/http-proxy vulnerable to prefix escape via WebSocket path traversal","id":"CVE-2026-15631","kev_date_added":null,"published":"2026-07-18"},{"cvss_score":7.5,"headline":"@fastify/http-proxy vulnerable to prefix escape via backslash dot-segments","id":"CVE-2026-85124","kev_date_added":null,"published":"2026-09-03"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"yes","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-07-15","vendors":["@fastify/reply-from"]},"summary":"Attackers can strip proxy-added security headers by abusing the Connection header, bypassing access controls in Fastify proxy libraries.","url":"https://insights.sbomify.com/CVE-2026-33805/"}